Patent Literature 1 discloses a wireless receiver drive that is attachable in a cell box of an external load of an electric toy etc. This wireless receiver drive is configured as a so-called switching power supply and changes, with a wireless module, a duty cycle of a drive signal of a transistor interposed between a held cell and an external terminal in accordance with a user instruction received via a wireless receiving unit, thereby changing a driving voltage to an external load device, whereby operation of the external load device such as an electric toy can be controlled. The wireless receiver drive further has a function of controlling power supply of the wireless receiving unit in accordance with an external switch of the external load device, thereby realizing an effect of preventing the cell from exhausting.
There are various demands such as preventing a cell from being further exhausted, as well as grasping a timing to swap a cell.